Removal of chlorophenols from aquatic systems with dye-affinity microbeads

Abstract

Cibacron Blue F3GA carrying pHEMA microbeads were investigated as dye-affinity sorbents for removal of chlorophenols (i.e. phenol, m-chlorophenol, p-chlorophenol and 2,4,6-trichlorophenol). PHEMA microbeads were prepared by modified suspension polymerization of HEMA in the presence of an initiator (azobisisobutyronitrile). These microbeads, with a swelling ratio of 55% and carrying 16.5 μmol Cibacron Blue F3GA/g polymer, were then used in the removal of chlorophenols from aqueous media. Adsorption rates of chlorophenols were very high, and equilibrium was achieved in about 20 min. The maximum adsorptions of chlorophenols onto the Cibacron Blue-carrying microbeads were 88.8 μmol/g for phenol, 94.6 μmol/g for 2,4,6-trichlorophenol, 97.6 μmol/g for p-chlorophenol and 109.1 μmol/g for m-chlorophenol. The affinity order was as follows: m-chlorophenol>p-chlorophenol>2,4,6-trichlorophenol>phenol. The adsorption of chlorophenols decreased with increasing pH. Desorption of chlorophenols was achieved using methanol solution (30%, v/v). The Cibacron Blue F3GA-carrying microbeads are suitable for repeated use for more than five cycles without any noticeable loss of adsorption capacity.